The invention relates to an anti-lock apparatus. Such anti-lock apparatus is known from the German Offenlegungsschrift No. 25 31 016 now German Pat. No. DT25 31 016 A1.
In the above-referred to known apparatus, the main brake cylinder piston is employed for the purpose of pressure modulation. Integrated brake force boosters are also already known, which operate with a travel-limiting spring, a brake valve and the appropriate hydraulic energy supply. When the energy supply is intact, the brake pedal push rod can cover an idle path distance which corresponds to the stroke of the path simulator, until it comes into contact with the main brake cylinder piston. In such an apparatus, it is assured, by means of particular features, that when the anti-lock means is operating to reduce the pressure to a low pressure level, the main brake cylinder piston can be driven back into the outset position without being contacted by the brake pedal push rod. If the auxiliary force fails, by means of particular features, the idle path distance noted above between the pedal push rod and the piston is eliminated; the push rod then comes into direct contact with the piston so that immediately upon the pedal's actuation, pressure can build up in the closed brake circuit.